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VOICE-OVER: Welcome to one of ConsExpo Web's online tutorials.
This video will give you insight into the exposure estimated...
by the spray models available in ConsExpo Web.
Many consumer products are applied by spraying...
and there is an increasing trend of spray applications.
Examples are air fresheners, deodorants, fly sprays, adhesives and so on.
Spraying of those products leads to the release of a substance...
as an aerosol into the air or onto a surface...
depending on the purpose of the application.
The release of the substance of interest from an aerosol into the air...
can be modelled using the spray models in ConsExpo Web.
Two models are currently available.
A low-tier model describing the instant release of a substance into the air...
and a more sophisticated model called the spray model.
The model's methodology is presented in a real-life scenario...
of a person using an air freshener in their living room.
The residential setting consists of a room in which a person uses the spray.
The room can be described by providing the room volume and room height.
The user of the spray product can be described by providing information...
on body weight and inhalation rate.
In this example, the user is an adult.
Once you have entered information about the room and the user...
the next inputs relate to the aerosol and its constituents.
Next, describe the behaviour of the sprayed aerosols to a number of model parameters.
The duration of spraying.
The mass generation rate...
describing the amount of product released per unit of time.
The former two combined provide the total released amount.
The airborne fraction...
which is the fraction of aerosols remaining airborne and thus available for inhalation.
The particle size distribution of the aerosols and how they disperse across the room.
And finally, the removal of aerosols from the air...
by gravitational settling and ventilation of the room.
The physics of release and dispersion are quite complex.
The instant release model simplifies the release and behaviour...
of the spray and the substance.
It makes no allowance for the fact that some substances...
are released as aerosols or vapours.
Furthermore, it does not take into account...
whether the product is used on a surface or not...
which may affect the airborne fraction.
Instead, it assumes that a specified product amount...
is instantaneously released into the air.
This model provides a conservative estimate of the concentration in the air...
and is used for situations where:
a quick conservative estimate of the exposure is desired...
information on the spray application and its use are lacking...
volatile substances with a vapour pressure above 1 Pa are released...
by the spray application.
Such volatile substances evaporate almost immediately due to the high release area.
If additional product data are available and refinement is needed...
the spray model can be used.
Similar to the first-tier approach, you need to enter the duration of spraying...
mass generation rate and exposure duration to describe the product use.
Additional input is needed to describe the airborne fraction...
and particle size distribution.
The airborne fraction describes the amount of spray that is released into the air.
This depends on the direction of the spray and type of spray product...
meaning for example a trigger spray or aerosol.
The particle size distribution is an important parameter...
that determines what happens to the spray.
Based on diameter size...
the model simulates gravitational settling within a room.
This is used to estimate the duration that spray will be available in the air.
The smaller the spray amount, the longer it floats in the air and can be inhaled.
Besides gravitational settling...
the model assumes an even distribution of aerosols across the room.
In some cases, this assumption is not justified.
When sprayed towards a person...
you can assume that there is an initial cloud surrounding the breathing zone.
The model crudely splits the first moments of release into the cloud...
after which immediate dispersion into the room is considered.
A second way of removing spray is by ventilation.
This works in a similar way across inhalation models...
and assumes a certain exchange with fresh air.
When using ConsExpo Web...
the desired information is to be provided by the user.
We use the example of an air freshener to show the functionality of the model.
Please note the insert fields for the particle size distribution...
and the option to provide raw data.
We run through the input fields providing information on spray duration...
mass generation rate, airborne fraction and particle size distribution...
which requires the median particle size and coefficient of variation.
Furthermore, we wish to highlight the requested cut-off diameter for inhalation.
This means that smaller aerosols are available for inhalation...
but bigger aerosols only for oral exposure.
Note that bigger aerosols will drop to the floor rapidly...
but some may still end up in the nasal and oral cavities...
where they are assumed to be ingested.
If you are interested in the integrated exposure to a spray...
you need to tick the box marked 'include oral non-respirable material exposure'.
After completing the insert fields, the model can be simulated.
Running the spray model with the example in mind...
yields results for the concentrations in the air, exposure estimates...
and graphs of the exposure event and how it evolves over time...
defined by the exposure duration.
We hope the tutorial has helped you to familiarise yourself with ConsExpo Web.
Our support does not end here.
Visit the ConsExpo website for help pages...
that provide information on ConsExpo Web and a user manual.
You can also access the 'i' and '?' icons within the software...
which are there to give you extra help when needed.
If you still have questions or need assistance...
please contact us at consexpo@rivm.nl.
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